1. Field of the Invention
The present invention relates to an image input-output apparatus having operation modes such as copying, printing, image reading etc. and a method therefor.
2. Related Background Art
The image input-output apparatus having such plural functions, generally called multi-function printer or multi-function copier (registered trade mark), can be classified into the following two categories.
1) A first type is so constructed as to execute as many functions as possible at the same time. An example of the configuration of the first type shown in FIG. 16.
Referring to FIG. 16, there are provided an image input unit 701; an operation panel 702 for entering various commands; an image processor unit 703 for applying predetermined image processing on the image read by the image input unit 701 in order to enable printing by a printer engine unit 709; an operation panel interface (I/F) 704; a main controller unit 705 for controlling the entire apparatus according to a control program stored in a ROM 707; a network I/F 706 for connection with a network; a ROM 707; RAM's 708, 712 used for example as a work memory; and printer engine 709, and a printer engine I/F 711.
Such apparatus is divided, as shown in FIG. 16, in a section 700 including the image input unit 701, the printer engine 709, the RAM 712, the image processor 703 and a CPU 705a and principally realizing the function of the digital copying apparatus, and a section 721 including a memory composed of the ROM 107 and the RAM 708, the network I/F 706 and a CPU 705b and effecting, in the CPU 705b, conversion of the document data transmitted through the network I/F 706 into a dot pattern printable by the printer engine 709.
For this reason, as shown in FIG. 16, there are provided completely separate two RAM's 707, 712 as the data work memories.
2) A second type is designed for a reduced cost, realizing multiple functions at a cost as low as possible and sacrificing the simultaneous functions in the first type.
However, the configuration as shown in FIG. 16 is inevitably associated with a considerably high cost, because of the necessity of the separate memories mentioned above. For example there is at least a memory capacity of 8.5 Mbytes, including 4 Mbytes for storing the image data entered by a scanner, in binary data of A4 size at 600 dpi, 4 Mbytes for a bit map memory for printing with a full bit map in binary data of A4 size at 600 dpi, and 0.5 Mbytes for a page memory before development into the bit map memory.